httpdir - dir.go

  // Package httpdir provides an in-memory implementation of http.FileSystem.
  package httpdir // import "vimagination.zapto.org/httpdir"
  
  import (
  	"io"
  	"io/fs"
  	"net/http"
  	"path"
  	"strings"
  	"time"
  )
  
  // Convenient FileMode constants.
  const (
  	ModeDir  fs.FileMode = fs.ModeDir | 0o755
  	ModeFile fs.FileMode = 0o644
  )
  
  // Default is the Dir used by the top-level functions.
  var Default = New(time.Now())
  
  // Mkdir is a convenience function for Default.Mkdir.
  func Mkdir(name string, modTime time.Time, index bool) error {
  	return Default.Mkdir(name, modTime, index)
  }
  
  // Create is a convenience function for Default.Create.
  func Create(name string, n Node) error {
  	return Default.Create(name, n)
  }
  
  // Remove is a convenience function for Default.Remove.
  func Remove(name string) error {
  	return Default.Remove(name)
  }
  
  // Dir is the start of a simple in-memory filesystem tree.
  type Dir struct {
  	d dir
  }
  
  // New creates a new, initialised, Dir.
  func New(t time.Time) Dir {
  	return Dir{
  		dir{
  			modTime:  t,
  			contents: make(map[string]Node),
  		},
  	}
  }
  
  // Open returns the file, or directory, specified by the given name.
  //
  // This method is the implementation of http.FileSystem and isn't intended to
  // be used by clients of this package.
  func (d Dir) Open(name string) (http.File, error) {
  	n, err := d.get(name)
  	if err != nil {
  		return nil, err
  	}
  
  	return n.Open()
  }
  
  func (d Dir) get(name string) (namedNode, error) {
  	name = path.Clean(name)
  	if len(name) > 0 && name[0] == '/' {
  		name = name[1:]
  	}
  
  	n := namedNode{"", d.d}
  
  	if len(name) > 0 {
  		for _, part := range strings.Split(name, "/") {
  			nd, ok := n.Node.(dir)
  			if !ok {
  				return namedNode{}, fs.ErrInvalid
  			}
  
  			dn, ok := nd.contents[part]
  			if !ok {
  				return namedNode{}, fs.ErrNotExist
  			}
  
  			n = namedNode{part, dn}
  		}
  	}
  
  	return n, nil
  }
  
  // Mkdir creates the named directory, and any parent directories required.
  //
  // modTime is the modification time of the directory, used in caching
  // mechanisms.
  //
  // index specifies whether or not the directory allows a directory listing.
  // NB: if the directory contains an index.html file, then that will be
  // displayed instead, regardless the value of index.
  //
  // All directories created will be given the specified modification time and
  // index bool.
  //
  // Directories already existing will not be modified.
  func (d Dir) Mkdir(name string, modTime time.Time, index bool) error {
  	_, err := d.makePath(path.Clean(name), modTime, index)
  
  	return err
  }
  
  func (d Dir) makePath(name string, modTime time.Time, index bool) (dir, error) {
  	name = strings.TrimPrefix(name, "/")
  	td := d.d
  
  	for _, part := range strings.Split(name, "/") {
  		if part == "" {
  			continue
  		}
  
  		if n, ok := td.contents[part]; ok {
  			switch f := n.(type) {
  			case dir:
  				td = f
  			default:
  				return dir{}, fs.ErrInvalid
  			}
  		} else {
  			nd := dir{
  				index:    index,
  				contents: make(map[string]Node),
  				modTime:  modTime,
  			}
  			td.contents[part] = nd
  			td = nd
  		}
  	}
  
  	return td, nil
  }
  
  // Create places a Node into the directory tree.
  //
  // Any non-existent directories will be created automatically, setting the
  // modTime to that of the Node and the index to false.
  //
  // If you want to specify alternate modTime/index values for the directories,
  // then you should create them first with Mkdir.
  func (d Dir) Create(name string, n Node) error {
  	dname, fname := path.Split(name)
  
  	dn, err := d.makePath(dname, n.ModTime(), false)
  	if err != nil {
  		return err
  	}
  
  	if _, ok := dn.contents[fname]; ok {
  		return fs.ErrExist
  	}
  
  	dn.contents[fname] = n
  
  	return nil
  }
  
  // Remove will remove a node from the tree.
  //
  // It will remove files and any directories, whether they are empty or not.
  //
  // Caution: httpdir does no internal locking, so you should provide your own if
  // you intend to call this method.
  func (d Dir) Remove(name string) error {
  	dname, fname := path.Split(name)
  
  	nn, err := d.get(dname)
  	if err != nil {
  		return err
  	}
  
  	if nd, ok := nn.Node.(dir); ok {
  		return nd.Remove(fname)
  	}
  
  	return fs.ErrInvalid
  }
  
  // Node represents a data file in the tree.
  type Node interface {
  	Size() int64
  	Mode() fs.FileMode
  	ModTime() time.Time
  	Open() (File, error)
  }
  
  type namedNode struct {
  	name string
  	Node
  }
  
  func (n namedNode) Name() string {
  	return n.name
  }
  
  func (n namedNode) IsDir() bool {
  	return n.Mode().IsDir()
  }
  
  func (n namedNode) Sys() any {
  	return n.Node
  }
  
  func (n namedNode) Open() (http.File, error) {
  	f, err := n.Node.Open()
  	if err != nil {
  		return nil, err
  	}
  
  	return wrapped{n, f}, nil
  }
  
  // File represents an opened data Node.
  type File interface {
  	io.Reader
  	io.Seeker
  	io.Closer
  	Readdir(int) ([]fs.FileInfo, error)
  }
  
  type wrapped struct {
  	fs.FileInfo
  	File
  }
  
  func (w wrapped) Stat() (fs.FileInfo, error) {
  	return w.FileInfo, nil
  }